/*
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 */

package test;

import javax.swing.event.ChangeEvent;

/**
 *
 * @author Administrator
 */
public class test {
    public static void main(String argv[]){
        String letGroup = "SN".substring(0, 1);

System.out.println(letGroup);
    }

    public void useChange(){
        String str="aaa";
        change(str);
        System.out.println(str);


    }

    public void change(String str){
        str="bbb";
    }

}
